The present invention relates to two-way optical communication systems, and more particularly to a transmitter-receiver apparatus comprising coaxial couplers.
A key component of two-way optical transmission systems is the transmitter-receiver (Tx/Rx) package. Such packages were originally fabricated with 1.times.2 or 2.times.2 couplers in combination with standard transmitters, such as laser diodes or in some applications, light emitting diodes, and standard receivers, such as PIN diodes. Such a system is disclosed in the publication, C. H. Henry et al, "Glass Waveguides on Silicon for Hybrid Optical Packaging", Journal of Lightwave Technology, vol. 7, No. 10, October, 1989, pp. 1530-1539.
U.S. Pat. No. 5,177,803 discloses a transmitter-receiver apparatus in which the standard coupler is replaced by a coaxial coupler. The coaxial coupler is a cylindrically-shaped device having a ring waveguide that is radially spaced from a central core waveguide. The longitudinally central region of the device is necked down to provide the desired type of coupling between the ring and core waveguides. At one end of the device the core waveguide is connected a transmission optical fiber. At the other end, an annular light detector is situated immediately adjacent the ring waveguide, and light is coupled from a source to the core waveguide through an aperture in the light detector. The light source and detector must be separately aligned with the core and ring waveguides, respectively.